A station is a subsystem of a conveyor. Items inserted on a conveyor are conveyoritems. If you want them to be assembled then one item leaves the system and becomes a subnode of the container item. Such an operation needs an exit transfer to let leave the item on a conveyor. This part of your question can you also realize just by Flexscript or process flow without the need of an exit transfer. The function that assembles items is called moveobject as a Flexscript command or Process Flow activity.
On a station that dissembles items you need to insert an item in an entry transfer, because it must become a conveyoritem again. This operation is not intended to be done by source code. You must have an entry transfer, which will manage the gap to pass an item into a conveyor system. Easiest would be you move the stacked item to a queue object by Flexscript or process flow. Then this queue will sends its content to this conveyor near your station into a site entry transfer.
You can get a new reference to your assembled item by properties first, last, rank or subnodes.
Hint: If you don’t want to see the queue, then you can hide it visually.
